Piston switch



HAQSAZQ) Aug. 21, 1923;

G. H. CHAPMAN PISTON SWITCH Filed April 10 III/I 2 2921 J 7100mm? 560790H Chapman;

and

Patented ne 21,1923.

: chosen H. CHAPMAN,

insane OF CHICAGO, ILLINOIS.

ris'rou swrron.

To all whom it may concern:

Be it known that I, GEORGE H. CHAPMAK, aacitizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Piston Switches, of

which the following is a specification.

This invention relates to electric switches of the piston or push-buttontype, the invention being designed mainly, although not exclusively, asan improved piston I switch for use on pipe-organs to 'close' electriccircuits for magnets which operate stop combination switches. 1

Among the objects ofthe invention are, to provide a piston switch ofgreater durability steadiness of movement than the switches of this typeheretofore used, to

provide a piston switch permittingone side of the circuitto be groundedonto the piston guide orshell, thus saving room which has heretoforebeen taken. up by the feed contact, to provide a piston switch adaptedto employ two or more wide contacts in co-operation with the movableelement of the switchwhich enables .a heavy current to be used anddistributes the arcing over a large contact area, to prov deaconstruction wherein the movable member of the switch is-securely heldagainst turning on its axis while being guided in its endwise movement,to provide a construction which may readily be'assembled anddisassembled for purposes of renewals and repairs; and, generally, toprovide an improved and more eflicient piston switch of the characterdescribed.

These, and other objects and advantages of the invention, will'beapparent to persons skilled inthe art as the same becomes betterunderstoodby reference to the follow ing" description, taken inconnection with the accompanying drawing in which I have illustrated'onepractical embodiment of the invention, and wherein Fig. 1 is a frontelevationof a fragment of the key shp of an organ console having myimproved piston switch'applied thereto;

Fig. 2 is a top plan view of Fig. 1;

-Fig. 3 is an enlarged transverse section V on the line 3-8 ofFig..2

- Fig. 4; is a: bottom plan, viewed from the under side of Fig.2; and

Fig. 5- is a rear elevation, as seen from thetop of Fig. 4:.

-Referring. to the drawing, designates Application filed April 10, 1922.Serial No. 551,097.

as an entirety a short section of a bar of wood or like non-conductingmaterial, constituting a part of the front pin-rail, and 11 is thekey-slip secured to the bar by screws 12. In, and crosswise of the bar10, 1s formed a round socket13, the openend of which registers with ahole 14: formed through the key-slip 11. Within the socket 13 and hole14 is fitted a hollow cylindrical shell 15 of brass or otherelectrically conductive material. The shell 15 is closed at its rear endby a centrally apertured wall 16 formed with a central annular boss or'mandrel 17. The bar 10 on its lower side is formed with a transversegroove 18 preterably located in the same vertical plane with the axis.ot'the shell 15.

' Slidably mounted in the rear wall 16 and boss 17 of the shell is thestem 19 of a slidable contact member, this latter carrying an integralcontact head 20 consisting of a rectangularly bent extension of the stem19, and a guide member 21 formed as 'a rectangularly bent extension ofthe head 20, paral lel with the stem 19 and slidably fitting theguidegroove 18. On the head 20 is preferably soldered a contact strip 22 ofsilver or other metal suitable for electrical contact I purposes.

Attached to the bar 10 are a pair of leaf spring contacts 23 and 2 1which, as clearly shown in Figs. 1 and 5, overhang the head 20 of theslidable contact member; the members 23 and 24 being disposed atslightly ditiereut angles, as shown in Fig. 1, so that, as the slidablecontact member is pushed inwardly, contact is first made with the strip23.. and later with the companion strip 24.

Slidably mounted in the shell 15 is the piston 25 of insulatingmaterial, carrying on its outer end the usual ivory push button 26.Theinner end of the piston 25 is countersunk to form a well or socket27, from the bottom of which latter extends a tapped hole 28 into whichthe outer threaded end-of the contact stem 19 is secured. Seated andguided within the well 27 of the plunger is the first-touch coil.compression spring 29, the other end ofwhich is centered on the boss ormandrel 17 and abutsagainst the bottom wall 16 of the shell. Surroundingthe spring 29 and footed on the rear wall 16 of the shell is thesecond-touch and heavier coil spring 30 that is called into actionthrough contact with the inner end of the piston only after the latterhas been pushed inwardly far enough to close the first-touch contactwiththe strip 28.

Mounted on and extending lengthwise of the bar 10 is a metal feed strip31 that is electrically connected to the shell 15 by a wire 32 (Fig. 3).

In practice, the feed strip 31 (which may serve a number of pistonswitches mounted side by side lengthwise of the bar 10) is connectedthrough a circuit wire, indicated at 33 inFig P J, with one side of abattery or'other source of current, while circuit wires 34 and (Fig. 5)lead from the contacts 2st and 23 through electromagnets which. in turnogerate stop combination switches, and thence to the other side of thebattery or other current generator, hen the piston 25 is pushed inwardlyfar enough to close the circuit through contacts 22 and 23, thefirst-touch compression spring 29 alone is compressed. Ii": it isdesired to closethe other circuit through contacts 22 and 24, the pistonis pushed all the way in, callinginto action the second-touchcompression spring 30. The instant the piston is released, it isinstantly returned by the Lao springs to outermost position; a feltstrip 36 (Fig. 3) preferably being employed as a buffer to limit theoutward movement of the-piston through engagement with the contact head20. 7

Among the advantages which the described structure possesses there maybe mentioned the-following: The usual felt bushiiig'encircling thepiston, which soon wears out and permits a wabbly movement of thelatter, and consequently a lost sidewise motion of contact, as well, is,in the present. structure, replaced by the metal shell 15 which affordsa long and steady guideforthepiston, and also permits one sideot thecircuit to be grounded therethrough. The described construction providesample guiding and centering means for both of the springs-29 and 30,preventing buckling and deformation of the latter holding one s'irinentirel se arate from a l s .V P the Otl161SP1lI1g, and insuring theirproper and eiiicient' action. The metal shell 15 with 2 its relativelythick rear wall 16 and annular the shell) bent extension 20 thereof:affords a wide boss 17 affords a substantial guide and support; for thestem of the sliding contact member; also a liberal area for electricalcontact between the current (grounded to and'thesliding stem; thelaterally --contact head for'co operation with a plurality" of contact;strips; and, finally, the

offset extension met the slidingcontact rmemben being guided in thegrooveor slot .18 holds the contact head 20 strongly against any lateralswinging movement, thus insuring the reciprocation of the slidingcontact memberalways in the same plane, and also within the holdingpiston turning. In many constructions, the ribbon strips 23 and 24 arereplaced by small round w1res,-;and where this is done, thedescribedconstruction at: fords room for a, considerable number of such narrowcontacts side by side." The'described construction effectivelyeliminates all liability to stick because of friction and lost motion;and the counter-boring of the piston allows a maximum length forthefirsttouch spring with aminimuin. space, while the second-touch springisenclosed' within the same brass shell and supported laterally by thelatter. By having; both springs contained within the circumference ofthe pistoii, it is possibleto use closer centers, when assemblingseveral ofthese piston switches in one bar or strip. Furthermore, bothsprings are easily accessible from the front by merely unscrewing thepiston 25- from the stem 19. I I 3 Although I have shown and describedmy invention as embodied ina piston switch-tor" organs, and contemplate,that'such willvbe 7 its principal use, it is manifest that the prin-:

ciple of theinvention may findembodi-ment in circuitcontrollingswitches'of thistype forotlier purposes and in otherrelations. i

Hence the invention is not limited'to its application' and use to and,on organs, nor'to the precise details ofstruct-ureand arrangementshown,but maybe modified and varied purview'and scope of the appended claims.

I claim 1. In a piston switch of the character described, thecombinationwith a. support, of

a metal shell of uniform internal diameter mounted therein, a circuitline connected to said shell, a piston slidablv fitting withinprojecting through said shell and having a laterally extending head, afixed contact member mounted on said support and cooperating with saidhead, a spring in said shell normally holding said contact membersseparated, and means for preventing saidfirst-named contact member yfrom turning on its longitudinal axis. v

3. In a pistonswitch of the character described, the combination with asupport, of

a cylindrical metal shell of uniform internal" r a fixed contact membermounted on said support and co-operating with said firstnamed contactmember, a circuit line connected to said shell and to said fixed contactmember, and a compression spring in said shell encirclingsaidfirst-named contact .member between the inner end of said shell and saidpiston for forcing the latter outwardly and thereby maintaining saidcontact members separated.

4. In a piston switch of the character described, the combination with asupport, of a cylindrical metal shell of uniform internal diametermounted therein, a circuit line connected to said shell, a pistonslidably fitting within and guided throughout substantially its entirelength by said shell, a contact member comprising'a stem portionattached to said piston and extending through the rear end of said shelland a laterally extended head portion, a fixed contact member mounted onsaid support and co-op-erating with. the head portion of saidfirst-named contact member, a spring in said shell for forcing saidpiston outwardly and separating said contact members, and co-operatingguides on said support and said first-named contact member operating tomaintain the latter against turning on its longitudinal ax1s. 1

5. In a piston switch of the character described, the combination of acylindrical metal shell of. uniform internal diameter having a'centrallyapertured'rear end wall, a piston slidably fitting within and guidedthroughout substantially its entire length by said shell andcounter-bored at its inner end to provide a spring supporting chamber, acontact rod attached to said piston and extending through said chamberand the aperture of said end wall, and a coil compression springencircling said contact rod and supported atits outer end in said pistonchamber and abutting at its inner end against said end wall.

6. In a piston switch of'the character describe-d, the combination of acylindrical metal shell having a centrally apertured rear end wallformed with a central annular boss on its inner side, a piston slidablyfitting said shell and centrally counter-bored at its inner end toprovide a spring supporting chamber, a contact rod attached to saidpiston and extending through: said chamber and said annular boss and endwall, a first touch coil spring encircling said contact rod andsupported at its outer end in said piston chamber and at its inner endcentered on said boss, and a second-touch shorter compression springencircling said first-named spring and reacting against the innerannular end of said piston during the last portion of the inwardmovement of the latter.

7. In a piston of the character described, the combination of a supportformed with a transverse socket and a transverse groove at i one side ofsaid socket, a cylindrical shell mounted in said socket, a pistonslidably fitting said shell, a contact member attached to said piston,said contact member having a stem portion extending through the rear endof said shell, a laterally extending head portion, and a guide portioncontinuous with said head portion and slidably engaged with said groove,and a spring Within said. shell reacting against said piston.

8. In a piston switch of the character described, the combination of asupport formed with atransverse socket and a transverse groove at oneside of said socket, a cylindrical shell mounted in said socket, apiston slidably fitting said shell, a contact member attached to saidpiston, said contact member having a stem portion extending through therear end of said shell, a laterally extending head portion, and a guideportion continuous with said head portion and slidably engaged with saidgroove, a plurality of leaf spring contact members attached to saidsupport and overhanging the head portion of said movable contact member,and a spring within said shell reacting against said piston.

V GEORGE H. CHAPMAN.

